Subject:
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Re: Cleaning up the main homepage
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Newsgroups:
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lugnet.admin.general
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Date:
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Sun, 12 Mar 2000 19:23:43 GMT
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Highlighted:
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In lugnet.admin.general, Todd Lehman writes:
> > This may be something you want to explain further on the page (or is it
> > too geeky??)
>
> Probably not too geeky and probably worth explaining somewhere. One
> undesirable effect in particular is if you say
> -.loc
> you end up removing lugnet.games.lego.loco! :-) The fix for that is simply
> to use
> -.loc.
> or
> -lugnet.loc.
> instead.
Prolly also worth explaining somewhere that the expression is compiled
left-to-right and is therefore direction-sensitive. That is,
-.loc. +.loc.us.ca
is very different from
+.loc.us.ca -.loc.
The string expression is compiled into a code expression which looks like this:
exclude = (... ((((FALSE) lop1 m1) lop2 m2) lop3 m3) ...)
where the lop's are either logical-OR or logical-AND, and the m's are either
match or not-match. Thus for the cases above, the resulting expression are:
-.loc. +.loc.us.ca =>
exclude = (((FALSE) OR ~".loc.") AND NOT ~".loc.us.ca")
+.loc.us.ca -.loc. =>
exclude = (((FALSE) AND NOT ~".loc.us.ca") OR ~".loc.")
--Todd
p.s. It's interesting to note that in languages in which FALSE is 0 and TRUE
is 1, the expression (X > Y) is the same as (X AND NOT Y). This is a trick
from the "good old days" of assembler back when saving 2 cycles mattered more
often and compilers weren't very smart. I think it's especially fun because
in pure mathematics, the AND symbol is ^ (not &) and the OR symbol is v (not |)
which makes < and > even more fun relative to that. :-)
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Message is in Reply To:
 | | Re: Cleaning up the main homepage
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| (...) That would be ever so slightly slower than an empty string, yes. I'm not sure it could be easily measured, though...talking probably something on the order of a 10^-5 second difference. (...) It's doing pure & simple character matchines, ya, (...) (24 years ago, 12-Mar-00, to lugnet.admin.general)
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